1. Field of the Invention
The present invention relates to an image processing apparatus, which is capable of performing wireless communication with a host apparatus, a control method for the image processing apparatus, and a storage medium storing a control program therefor.
2. Description of the Related Art
A standard of wireless USB, which is a wireless version of a USB interface that is one of standards to connect a peripheral device to a computer, is known.
In wireless USB communication, a plurality of host apparatuses (PCs etc.) cannot communicate with one device (an image processing apparatus etc.) simultaneously, and one host apparatus can communicate with only one device. This is defined by the standard of the wireless USB (Wireless USB Specification Rev. 1.0).
An outline when a connection of one-to-one communication is established between the host apparatus and the device will be described with reference to FIG. 22.
FIG. 22 is a schematic view showing a system example in which the wireless USB communication is performed between the host apparatus 10 provided with a wireless USB antenna 11 and the device 20 provided with a wireless USB antenna 21. It should be noted that the host apparatus 10 may be a personal digital assistant (PDA) etc. besides a PC.
The host apparatus 10 transmits a wireless signal including host information (a host ID (CHID)). Receiving the wireless signal concerned, the device 20 retrieves a CC (a connection context) having a host ID that is identical to the received host ID from a storage device thereof. The CC consists of the host ID, a device ID, a connection key, etc.
When there is the CC having the host ID that is identical to the received host ID as a result of retrieving the storage device thereof, the device 20 transmits the device ID (CDID) to the host apparatus 10 to perform a connection request.
When receiving the connection request, the host apparatus 10 retrieves a CC having a host ID that is identical to the received host ID from a storage device thereof. When there is the CC having the host ID that is identical to the received host ID, the host apparatus 10 starts a connection process to establish the one-to-one communication with the device 20.
When the host apparatus 10 outputs a print request to the device 20, the above-mentioned connection process is performed. After the communication is established, the host apparatus 10 generates print data by an application thereof, and transmits the print data to the device 20 by encryption communication.
In order that the host apparatus 10 and the device 20 perform the connection process by the wireless USB communication and establish the encryption communication, it is necessary to perform an association process to associate the host apparatus 10 with the device 20.
The association process is usually performed before a first connection to share a common CC between the host apparatus 10 and the device 20. When the association process is once performed by the host apparatus 10 and the device 20, the wireless connection can be performed without performing a specific process at a second time or later.
In the wireless USB standard, a cable association model and a numeric association model are defined as the association process that associates the host apparatus 10 and the device 20.
The cable association model enables communication by the wireless USB between the host apparatus 10 and the device 20 after the host apparatus 10 is associated with the device 20 by connecting by a wired cable (an association process is performed) once.
The numeric association model enables communication by the wireless USE between the host apparatus 10 and the device 20 without particular operations after the host apparatus 10 is associated with the device 20 by the wireless USB communication.
For example, in the numeric association model, the host apparatus 10 and the device 20 are installed within an area that allows the wireless communication, and an association button of the device 20 is pushed. By pushing the association button of the device 20, the same numeric value of about four-digit is displayed on a display screen of the host apparatus 10 and a display screen of the device 20. The above-mentioned operations complete the association process.
Incidentally, the above-mentioned association process has a problem that a person other than a device owner (who is permitted to use the device) can communicate with the device without particular operations at a second connection or later as long as the person has completed the association process once. That is, since any host apparatuses can connect with the device if the association process goes so far as to be finished, a person who is not permitted to use the device can access the device easily.
In order to prevent such an unauthorized access, Japanese laid-open patent publication (Kokai) No. 2007-336287 (JP2007-336287A) discloses a technique that allows to execute the association process only when a password transmitted from the host apparatus matches a password stored in the device as a comparison result.
However, since the technique in the above-mentioned publication requires authentication with a password before executing the association process, there is a problem that a person who is not permitted to use the device can unauthorizedly access the device, when the person unauthorizedly obtained the password. In addition, the technique has poor usability to an authorized user who is permitted to use the device, because the user has to remember the password.